WINNIPEG -- A new study involving the University of Manitoba says hydroxychloroquine is not an effective treatment to prevent the development of COVID-19.

The results of the study, released Wednesday, come following a trial of the drug in the United States, Manitoba, Quebec, and Ontario.

The University of Manitoba participated in the study, which included McGill University, the University of Minnesota, and the University of Alberta.

"What we found out is that the drug was not effective at preventing symptoms of the COVID-19 disease, or the disease itself," Dr. Ryan Zarychanski, co-principal investigator of the clinical trial and a hematologist and critical care physician at the U of M and CancerCare Manitoba, told CTV News.

"This is not a failure per se, this is the successful completion of the trial; the resolution of a hypothesis with intention to move on and complete the other trials that we've started."

“While we had hope this drug would work in this context, our study demonstrates that hydroxychloroquine is no better than placebo when used as post-exposure prophylaxis within 4 days of exposure to someone infected with the new coronavirus,” said Dr. Todd Lee, associate professor of medicine in the Division of Infectious Diseases at McGill University, in a statement.

The trial involved 821 asymptomatic adults with household or healthcare exposure to someone with confirmed COVID-19 receiving Hydroxychloroquine or a placebo, four days following exposure.

According to the study, 107 of 821 of participants developed COVID-19, either confirmed with a test or symptomatically compatible disease, over the 14 days of follow-up. The study included both confirmed cases and probable cases, due to some lack of availability of diagnostic testing in the United States.

Among those who received hydroxychloroquine, 49 developed the disease, or compatible symptoms, such as fever or cough. A total of 58 people in the group that received the placebo developed COVID-19.

Two people were hospitalized, the study said, with one hospitalized in the hydroxychloroquine group, and one in the placebo group.

The study said no serious treatment-related adverse reactions were reported, including any heart arrhythmia. It adds more research and trials need to be conducted on the effectiveness of hydroxychloroquine.

"The drug was generally well-tolerated, although about 40 per cent of people had some side effects. They were all minor – but, more importantly, the drug did not seem to prevent infection in those who received it," Zarychanski said.

"There are other really important questions that still need answering with regard to this drug or other drugs – perhaps hydroxychloroquine may work to treat people with COVID-19 disease when they are sick in hospital, and that trial is ongoing."

The drug has been in the news in recent weeks as U.S. President Donald Trump told reporters he was taking the drug, despite it being unproven as a treatment for COVID-19.

Zarychanski said the messaging around the drug by some politicians is unfortunate.

"Hydroxychloroquine has been purveyed as something magical and a game-changer, but that was not based on science. That was based on opinion and largely uninformed opinions as well," he said.

He said this trial provides definitive information to give everyone answers.

"Although this drug is getting a lot of media attention, it's not the only drug trial that we are conducting and it's by far not the most promising agent under study."

He said they are working on a number of other COVID-19 trials that are ongoing for other anti-viral medications.

The study was published in the New England Journal of Medicine.

-with files from CTV's Vanessa Broadbent